The present invention concerns a shaft-rotated throttle disk for use in the intake pipe of an internal combustion engine, whereby the shaft is solid and the disk includes a body of material surrounding the shaft.
Throttle disks are employed to regulate the flow of a fluid medium through a pipe. Such disks are typically utilized in the intake pipe of an internal combustion engine. To minimize rheological losses on the part of the mixture of fuel and air flowing past the disk inside the intake pipe, the impedances at the surface and on top of the disk must be minimized. Decreasing the rheological losses helps to fill the engine's combustion chamber, increasing the engine's power and improving fuel economy.
The situation in the intake pipe must be definite and unambiguous for the engine to be satisfactorily adjusted and regulated. Precise regulation and adjustment of an idling internal combustion engine is possible only when a precisely known air leakage current, if any, is flowing past the throttle disk.
It is well known to regulate the mixture of fuel and air of an engine with a sheet metal throttle disk rotating in a slotted shaft. The disk is inserted through a slot in the center of the shaft and secured to the shaft, for example, by screws.
A throttle disk that actually surrounds the throttle shaft in an intake pipe is known from the German patent publication No. 2,934,216.
Methods of applying a coat of polymer to the inner surface of an intake pipe in the vicinity of a throttle valve are also known. Such methods are disclosed, for example, in German Patent No. 3,243,996.
One particular drawback of a sheet metal throttle disk extending through a slotted shaft is that its shape in the intake pipe inhibits the fluid flow, and losses occur. The engine's output decreases because fuel-air mixture is prevented from reaching the combustion chamber.
There are also considerable problems in sealing the slotted shaft with respect to the disk. Manufacturing tolerances that cannot be practically or economically eliminated prevent the shaft and disk from completely blocking the intake pipe. As a result, the idling internal combustion engine can be adjusted and regulated only with difficulty. If the throttle disk is constructed to surround a solid shaft, there will be drawbacks with respect to the life of the areas adjacent to the circumference of the throttle disk and to how well it is sealed with respect to the intake pipe. The very acute angle between the surfaces entails the risk of chips breaking away from the throttle disk edges, which are integral components of the disk and made of the same material, thereby affecting the engine's operation when the throttle disk is partly or completely closed.